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Editing: paginator.py
import collections.abc import inspect import warnings from math import ceil from django.utils.functional import cached_property from django.utils.inspect import method_has_no_args from django.utils.translation import gettext_lazy as _ class UnorderedObjectListWarning(RuntimeWarning): pass class InvalidPage(Exception): pass class PageNotAnInteger(InvalidPage): pass class EmptyPage(InvalidPage): pass class Paginator: # Translators: String used to replace omitted page numbers in elided page # range generated by paginators, e.g. [1, 2, '…', 5, 6, 7, '…', 9, 10]. ELLIPSIS = _('…') def __init__(self, object_list, per_page, orphans=0, allow_empty_first_page=True): self.object_list = object_list self._check_object_list_is_ordered() self.per_page = int(per_page) self.orphans = int(orphans) self.allow_empty_first_page = allow_empty_first_page def __iter__(self): for page_number in self.page_range: yield self.page(page_number) def validate_number(self, number): """Validate the given 1-based page number.""" try: if isinstance(number, float) and not number.is_integer(): raise ValueError number = int(number) except (TypeError, ValueError): raise PageNotAnInteger(_('That page number is not an integer')) if number < 1: raise EmptyPage(_('That page number is less than 1')) if number > self.num_pages: if number == 1 and self.allow_empty_first_page: pass else: raise EmptyPage(_('That page contains no results')) return number def get_page(self, number): """ Return a valid page, even if the page argument isn't a number or isn't in range. """ try: number = self.validate_number(number) except PageNotAnInteger: number = 1 except EmptyPage: number = self.num_pages return self.page(number) def page(self, number): """Return a Page object for the given 1-based page number.""" number = self.validate_number(number) bottom = (number - 1) * self.per_page top = bottom + self.per_page if top + self.orphans >= self.count: top = self.count return self._get_page(self.object_list[bottom:top], number, self) def _get_page(self, *args, **kwargs): """ Return an instance of a single page. This hook can be used by subclasses to use an alternative to the standard :cls:`Page` object. """ return Page(*args, **kwargs) @cached_property def count(self): """Return the total number of objects, across all pages.""" c = getattr(self.object_list, 'count', None) if callable(c) and not inspect.isbuiltin(c) and method_has_no_args(c): return c() return len(self.object_list) @cached_property def num_pages(self): """Return the total number of pages.""" if self.count == 0 and not self.allow_empty_first_page: return 0 hits = max(1, self.count - self.orphans) return ceil(hits / self.per_page) @property def page_range(self): """ Return a 1-based range of pages for iterating through within a template for loop. """ return range(1, self.num_pages + 1) def _check_object_list_is_ordered(self): """ Warn if self.object_list is unordered (typically a QuerySet). """ ordered = getattr(self.object_list, 'ordered', None) if ordered is not None and not ordered: obj_list_repr = ( '{} {}'.format(self.object_list.model, self.object_list.__class__.__name__) if hasattr(self.object_list, 'model') else '{!r}'.format(self.object_list) ) warnings.warn( 'Pagination may yield inconsistent results with an unordered ' 'object_list: {}.'.format(obj_list_repr), UnorderedObjectListWarning, stacklevel=3 ) def get_elided_page_range(self, number=1, *, on_each_side=3, on_ends=2): """ Return a 1-based range of pages with some values elided. If the page range is larger than a given size, the whole range is not provided and a compact form is returned instead, e.g. for a paginator with 50 pages, if page 43 were the current page, the output, with the default arguments, would be: 1, 2, …, 40, 41, 42, 43, 44, 45, 46, …, 49, 50. """ number = self.validate_number(number) if self.num_pages <= (on_each_side + on_ends) * 2: yield from self.page_range return if number > (1 + on_each_side + on_ends) + 1: yield from range(1, on_ends + 1) yield self.ELLIPSIS yield from range(number - on_each_side, number + 1) else: yield from range(1, number + 1) if number < (self.num_pages - on_each_side - on_ends) - 1: yield from range(number + 1, number + on_each_side + 1) yield self.ELLIPSIS yield from range(self.num_pages - on_ends + 1, self.num_pages + 1) else: yield from range(number + 1, self.num_pages + 1) class Page(collections.abc.Sequence): def __init__(self, object_list, number, paginator): self.object_list = object_list self.number = number self.paginator = paginator def __repr__(self): return '<Page %s of %s>' % (self.number, self.paginator.num_pages) def __len__(self): return len(self.object_list) def __getitem__(self, index): if not isinstance(index, (int, slice)): raise TypeError( 'Page indices must be integers or slices, not %s.' % type(index).__name__ ) # The object_list is converted to a list so that if it was a QuerySet # it won't be a database hit per __getitem__. if not isinstance(self.object_list, list): self.object_list = list(self.object_list) return self.object_list[index] def has_next(self): return self.number < self.paginator.num_pages def has_previous(self): return self.number > 1 def has_other_pages(self): return self.has_previous() or self.has_next() def next_page_number(self): return self.paginator.validate_number(self.number + 1) def previous_page_number(self): return self.paginator.validate_number(self.number - 1) def start_index(self): """ Return the 1-based index of the first object on this page, relative to total objects in the paginator. """ # Special case, return zero if no items. if self.paginator.count == 0: return 0 return (self.paginator.per_page * (self.number - 1)) + 1 def end_index(self): """ Return the 1-based index of the last object on this page, relative to total objects found (hits). """ # Special case for the last page because there can be orphans. if self.number == self.paginator.num_pages: return self.paginator.count return self.number * self.paginator.per_page
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